1. Field of the Invention
This invention relates generally to fluid conduits such as hoses and tubes, more particularly to heated fluid conduits, and specifically to fluid conduits heated using semiconductive resistance heating.
2. Description of the Prior Art
Selective Catalytic Reduction (SCR) vehicles, referred to in Europe as Euro V vehicles, are diesel powered motor vehicles which are compatible with the use of an operating fluid to reduce emissions. Typically, the SCR vehicle has a urea tank, separate from the fuel tank, which is used to carry an operating fluid such as an automotive urea solution, or the like. Automotive Urea Solution (AUS) is a solution of high purity urea in de-mineralized water. AUS is stored in a urea tank of an SCR vehicle and is sprayed into the exhaust gases of the vehicle in order to convert oxides of nitrogen into elementary nitrogen and water. An SCR vehicle may then advantageously satisfy various emission standards, such as the Euro V Emissions Standard.
Problematically, AUS freezes at a temperature of approximately minus eleven degrees centigrade. In order to ensure this method of reducing emissions in an SCR vehicle remains effective, the AUS needs to be maintained in a liquid state to allow injection
SCR vehicles generally rely on a heating wire or the like, which may be molded into or wrapped around the AUS hose or line to avoid freezing of the AUS. This is a rather inefficient and inflexible solution that requires a complete redesign of the fluid line to change its heating properties. Thus, to change the heating characteristics of an internal wire assembly, another production run of the hose must be produced and the resistance per foot is changed when the hose is being extruded by either changing the wire pitch, the wire size or adding more wires into the system, or a combination of all three.
Also, oil drilling rigs are being operated in harsher environments as oil is drilled for in Alaska and the Arctic and Antarctica. It is now not unusual for a rig to start up in minus sixty degree Fahrenheit weather. This cold weather has an adverse effect on equipment and hydraulic components on a drill rig. When starting up a hydraulic machine at these cold temperatures it is not unusual for the seals to rupture in valves and cylinders.